A conventionally known structure disposed in an exhaust passage of an internal combustion engine has a catalyst-carrying filter for capturing particulates contained in exhaust gas so as to burn the particulates, and a heater disposed upstream of the catalyst-carrying filter and adapted to activate the catalyst (see Japanese Unexamined Publication No. H09-310611). The heater is a honeycomb-type heating element formed by spirally winding a metal foil and a corrugated plate superposed on each other about a center electrode and generates heat through application of electricity to the center electrode and a counter electrode provided on the outer-circumference side of the heater.
According to a developed technique (see Japanese Unexamined Publication No. 20089-14239), a plurality of positive electrodes and a plurality of negative electrodes are provided on a metal foil at different positions, and by selecting any one positive electrode and any one negative electrode, only a partial region of the metal foil generates heat so as to produce a catalytic function on the metal foil.